Conventionally, oscillation type linear actuators having various constitutions are proposed as a driving source of a reciprocation type power shaver. In a conventional oscillation type linear actuator shown in Publication Gazette of Japanese Patent Application 8-3180610(first conventional art), two moving members are coupled by a coupling member having a spring function and displacing in a direction of reciprocal movement of the moving members, in order to prevent occurrence of uncomfortable vibration without losing a balance of oscillation of the moving members, even when a force is externally applied to one of the moving members oscillated in opposite phases with each other.
When a large load is applied to only one of the moving members while the moving members are respectively driven reciprocally in opposite phases, an amplitude of the oscillation of the moving member is suddenly made be reduced. The coupling member, however, transmits a motion of the other moving member to the moving member, so that the reduction of the amplitude of the moving member, to which the load is applied, is restricted. Consequently, the balance of the amplitudes of two moving members can be maintained.
In the first conventional art, a coil spring, however, is used as the coupling member having the spring function, so that it needs a space for disposing the coil spring between the moving members. Consequently, it has a problem that the entire size of the actuator becomes larger.
On the other hand, in another conventional oscillation type linear actuator shown in Publication Gazette of Japanese Patent Application 11-136921 (second conventional art), a plate spring is used as a coupling member with the aim of downsizing. An upper end portion of the coupling member is fixed on a chassis by a screw, and a lower end portions are respectively fixed on two moving members so that two moving members are coupled.
In this case, even though a space for disposing the coupling member can be made smaller in comparison with the case that the coil spring is used as the coupling member, it, however, has a problem that the function as the coupling member is deteriorated in comparison with one using the coil spring, since the upper end portion of the coupling member is kept under restraint on the chassis by the screw, and a motion of a moving member cannot be transmitted sufficiently to the other when a large load is applied to the other moving member.